1. FIELD OF THE INVENTION
The present invention relates to vitreous detector material and more particularly to inorganic vitreous detector material of high energy resolution, to a process of making such detector material, and to its use especially for determining the energy of particles of high energy.
2. DESCRIPTION OF THE PRIOR ART
Energy-rich particles and more particularly heavy ions and fission products, when impinging upon or penetrating into insulator materials, produce tracks or marks which can be made visible under a microscope, for instance after treatment with suitable solvents or etching means. In addition to the number of impinging particles, the energy of the particles recorded is of particular importance.
Thus it is known, for instance, that the track characteristics in solids permit to draw conclusions as to the energy of vertically impinging particles. See, for instance H. Ait-Salem et al. in "Nuclear Instruments and Methods" vol. 60 (1968), page 45; E. V. Benton et al. in "Nuclear Instruments and Methods" vol. 67 (1969), page 87; and G. Somogyi et al. in "Nuclear Instruments and Methods" vol. 63 (1968), page 189. In this connection the diameter of the etched hole proves a suitable value for the measurement. While with short etching times only a slight change of the diameter as a function of the energy of the fission products is obtained, a definite increase in the diameter of the etched hole in relation to the energy is observed on prolonged etching. For such a use, glasses have proved to be superior to plastics which show too slight a dependence on energy, or to crystals which, due to their properties of anisotropy, yield asymmetrical holes (see in this respect U. Hoppner et al. in "Nuclear Instruments and Methods" vol. 74 (1969), page 285.
In general, the etching times of glass materials bombarded with particles are, however, somewhat restricted. This is due, on the one hand, to the fact that by the "fringing out" of the holes, i.e. to the fact that the initially etched points of impact become irregular, an exact determination of the diameter of the hole is no longer possible and, on the other hand, to the fact that they can no longer be measured unequivocally due to too low a contrast in the microscope or even no contrast at all.